The ever increasing need for digital data storage has driven an ever increasing demand for improved magnetic data storage systems, such as magnetic disk drive systems. The magnetic disk drive includes a rotating magnetic disk, write and read heads that are suspended by a suspension arm adjacent to a surface of the rotating magnetic disk and an actuator that swings the suspension arm to place the read and write heads over selected data tracks on the rotating disk. The read and write heads are located on a slider that has an air bearing surface (ABS). The suspension arm biases the slider into contact with the surface of the disk when the disk is not rotating, but when the disk rotates air is swirled by the rotating disk. When the slider rides on the air bearing, the write and read heads are employed for writing magnetic impressions to and reading magnetic impressions from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.
The write head includes at least one coil, a write pole and one or more return poles. When current flows through the coil, a resulting magnetic field causes a magnetic flux to flow through the coil, which results in a magnetic write field emitting from the tip of the write pole. This magnetic field is sufficiently strong that it locally magnetizes a portion of the adjacent magnetic media, thereby recording a bit of data. The write field then travels through a magnetically soft under-layer of the magnetic medium to return to the return pole of the write head.
A magnetoresistive sensor such as a Giant Magnetoresistive (GMR) sensor or a Tunnel Junction Magnetoresistive (TMR) sensor can be employed to read a magnetic signal from the magnetic media. The magnetoresistive sensor has an electrical resistance that changes in response to an external magnetic field. This change in electrical resistance can be detected by processing circuitry in order to read magnetic data from the magnetic media.
As magnetic bit sizes decrease in order to accommodate ever increasing data density demands, the ability to maintain a stable magnetic signal on a media becomes ever more challenging. The smaller magnetic bit size and smaller magnetic spacing makes the magnetic bits less stable, and prone to data loss. One way to overcome this challenge is to increase the magnetic coercivity and magnetic anisotropy of the magnetic recording layer of the magnetic media. However, this also makes the magnetic media harder to write to, requiring a high magnetic write field to record to the media. This challenge is further exacerbated by the reduced size of the write head that is needed to record the smaller bit. As the write head becomes smaller, the amount of write field that it can produce is also reduced. Therefore, there remains a need for a magnetic recording system that can effectively record a stable magnetic signal to a recording media at very high data densities.